Intravascular stent device

ABSTRACT

A very small diameter intravascular stent device which may be used to occlude or partially occlude an aneurysm in the human brain which is comprised of a thin-walled skeletal cylindrical tube formed of undulating or sinusoidal elements which, when compressed, nest tightly with each other.

[0001] This is a divisional of U.S. application Ser. No. 10/163,248,filed Jun. 5, 2002, which claims the benefit of provisional patentApplication No. 60/298,325, filed Jun. 14, 2001.

BACKGROUND OF THE INVENTION

[0002] This invention relates to intravascular devices for implantationwithin a vessel of the body, and more particularly to a stent devicewhich may be used in the treatment of blood vessel disorders. Morespecifically, the intravascular device may take the form of an aneurysmcover to be used in the treatment of aneurysms which occur in the brain.

DESCRIPTION OF THE PRIOR ART

[0003] On a worldwide basis, nearly one million balloon angioplastieswere performed in 1997 to treat vascular disease, including bloodvessels clogged or narrowed by a lesion or stenosis. The objective ofthis procedure is to increase the inner diameter or cross-sectional areaof the vessel passage, or lumen, through which blood flows.

[0004] Another serious vascular defect is an area of weakened vesselwall that causes a bulge, or bubble, to protrude out in a radialdirection from the vessel. This type of defect is called an aneurysm. Ifuntreated, the aneurysm may continue expanding until it bursts therebycausing hemorrhaging from the vessel.

[0005] In an effort to prevent restenosis or treat an aneurysm withoutrequiring surgery, short flexible cylinders or scaffolds, made of metalor polymers, are often placed into a vessel to maintain or improve bloodflow. Referred to as stents, various types of these devices are widelyused for reinforcing diseased blood vessels, for opening occluded bloodvessels, and for defining an internal lumen to relieve pressure in ananeurysm. The stents allow blood to flow through the vessels at animproved rate while providing the desired lumen opening or structuralintegrity lost by the damaged vessels. Some stents are expanded to theproper size by inflating a balloon catheter, referred to as “balloonexpandable” stents, while others are designed to elastically resistcompression in a “self-expanding” manner.

[0006] Balloon expandable stents and self-expanding stents are generallydelivered in a cylindrical form, crimped to a smaller diameter and areplaced within a vessel using a catheter-based delivery system. Whenpositioned at a desired site within a vessel, these devices are expandedby a balloon, or allowed to “self-expand,” to the desired diameter.

[0007] One such stent for treatment of abdominal aortic aneurysms isdisclosed in U.S. Pat. No. 6,267,783 to Robert P. Letendre, et al. Thispatent discloses a self-expanding stent which may be used in thetreatment of aortic aneurysms. This device may be easily recapturedafter placement and repositioned to a new position within the vessel.This patent, assigned to a related company, is subsequently referred toand the disclosure therein is incorporated and made a part of thesubject patent application.

[0008] Another stent aneurysm treatment device is disclosed in U.S. Pat.No. 6,361,558, assigned to the same assignee as the present application.This patent discloses vasculature stents of various configurations whichmay be used as aneurysm covers for occluding, or partially occluding,aneurysms located at various positions along the blood vessels.

SUMMARY OF THE INVENTION

[0009] There is a need for an improved stent which may be easilydelivered to a vasculature site through a very small catheter, iscapable of being repositioned and which exhibits sufficient structuralintegrity and resilience under radial compressive forces. Moreparticularly, there is a need for such a stent that, in its compressedstate prior to delivery of the stent, has a diameter which is extremelysmall. Such a stent could be placed in a very small microcatheter forsubsequent positioning within a vessel of the human brain. Obviously,such vessels are extremely small and very tortuous throughout theirlength.

[0010] In accordance with one aspect of the present invention, there isprovided a self-expanding stent device which includes a small diameterskeletal tubular member. The skeletal tubular member is comprised of aplurality of cells which are formed by a plurality of generallyundulating members and a plurality of struts. The undulating members aregenerally parallel with the longitudinal axis of the tubular member andare generally parallel to each other. In addition, the undulatingmembers have a plurality of peaks. The undulating members and struts areinterconnected and have a repeating pattern in which the proximal endsof the struts are attached to the peaks of the undulating members andthe distal end of the struts are attached to the peaks of adjacentundulating members.

[0011] In accordance with another aspect of the present invention, theskeletal tubular member has a very small compressed diameter fordelivery within a vessel and a normally biased expanded diameter forretaining the stent against the walls of the vessel. As the tubularmember is compressed to its small diameter, the peaks of the undulatingmembers pull upon the proximal end of the struts and the distal ends ofthe struts pull upon peaks of adjacent undulating members therebycausing the cells of the tubular members to collapse and “nest”together. This nesting causes the skeletal tubular member to retain avery small diameter.

[0012] In accordance with another aspect of the present invention, theskeletal tubular member includes at least two proximal legs which extendgenerally parallel to the longitudinal axis of the tubular member andare attached to the proximal end of the tubular member. At least one ofthe proximal legs includes a T-shaped or I-shaped attachment flange.

[0013] In accordance with still another aspect of the present invention,the proximal legs are biased outwardly from the longitudinal axis of thetubular member. The proximal legs preferably include a radiopaque markerfor positioning the stent within a vessel.

[0014] In accordance with another aspect of the present invention, thetubular member includes at least one distal leg which extends generallyparallel to the longitudinal axis of the tubular member and is attachedto the distal end of the tubular member. The distal leg preferablyincludes a radiopaque marker for locating the distal end of the stent asthe stent is placed in a vessel.

[0015] In accordance with still another aspect of the present invention,there is provided a self-expanding stent device which includes a smalldiameter skeletal tubular member which is formed with a thin wall. Thewall of the tubular member includes a plurality of cells which areformed by a plurality of sinusoidal members and a plurality of struts.The sinusoidal members are generally parallel to the longitudinal axisof the tubular member and are generally parallel to each other. Eachsinusoidal member has a plurality of positive peaks and negative peaks.The sinusoidal members and the struts are interconnected and have arepeating pattern in which each strut connects a positive peak of asinusoidal member with a negative peak of an adjacent sinusoidal member.

[0016] In accordance with still anther aspect of the present invention,the skeletal tubular member has a very small compressed diameter fordelivery within a vessel and a normally biased expanded diameter forretaining the stent device against the walls of a vessel. As the tubularmember is compressed to its small diameter, the positive peaks of thesinusoidal members pull the struts, and the struts pull the negativepeaks of adjacent sinusoidal members thereby causing the cells of thetubular member to collapse with the result that the sinusoidal members“nest” together with adjacent sinusoidal members in order to provide avery small diameter stent device.

[0017] In accordance with still another aspect of the present invention,a self-expanding aneurysm cover is provided which when placed across ananeurysm of a blood vessel reduces, or obstructs, the flow of bloodbetween the aneurysm and its related blood vessel. The aneurysm coverincludes a small diameter skeletal tubular member which is comprised ofa plurality of cells which are formed by a plurality of generallyundulating members and a plurality of struts. The undulating members aregenerally parallel with the longitudinal axis of the tubular member andare generally parallel to each other. In addition, the undulatingmembers have a plurality of peaks. The undulating members and struts areinterconnected and have a repeating pattern in which the proximal endsof the struts are attached to the peaks of the undulating members andthe distal end of the struts are attached to the peaks of adjacentundulating members.

[0018] These and other aspects of the present invention and theadvantages thereof will be more clearly understood from the foregoingdescription in drawings of a preferred embodiment of the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 is an oblique prospective view of an intravascular stentconstructed in accordance with a preferred embodiment of the presentinvention;

[0020]FIG. 1a is an expanded view of the proximal portion of theretaining legs shown in FIG. 1;

[0021]FIG. 2 is a side elevational view of the intravascular stentillustrated in FIG. 1 with the tubular stent being cut along a line andflattened into a single plane; and,

[0022]FIG. 3 illustrates in more detail the proximal retaining legs ofFIG. 1a and the interconnecting elements between the intravascular stentand a positioning catheter.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0023]FIG. 1 illustrates a self-expanding stent device which is lasercut to form a thin-walled, skeletal tubular member 11 comprised ofnickel-titanium alloy. Once cut, the wall of the tubular member 11includes several openings, or cells 14. When the skeletal tubular member11 is placed over an aneurysm, a physician is able to deliver emboliccoils or other such devices through the cells 14 and into the aneurysm.The tubular member 11 also functions to cover the mouth of the aneurysmthus obstructing, or partially obstructing, the flow of blood into theaneurysm. Also, the tubular member 11 prevents medical devices such asembolic coils from escaping the aneurysm.

[0024] The preferred length of the skeletal tubular member 11 may rangefrom 0.0795 inches to 3.15 inches. The diameter of the tubular member 11varies depending on its deployment configuration. In a non-deployed orexpanded state, the diameter of the tubular member 11 may extend up toabout 0.4 inches. When the skeletal tubular member 11 is compressed tofit within the lumen of a deployment catheter, the diameter may bereduce to about 0.014 inches.

[0025] Attached to the proximal end 16 of the skeletal tubular member 11are three proximal legs 18, 18 a, and 18 b that extend longitudinallyfrom the tubular member 11. The proximal legs 18, 18 a, and 18 b arepreferably biased outwardly from the longitudinal axis of the tubularmember 11. This outwardly biased configuration aids in the deploymentsystem as subsequently described.

[0026] T-shaped or I-shaped attachment flanges 20, 20 a, and 20 b areattached to the tips of each proximal leg 18, 18 a, and 18 b. FIG. 1adescribes the T-shaped or I-shaped flanges 20, 20 a, and 20 b in moredetail. Attached to the distal end 21 of the skeletal tubular member 11are two distal legs 22 and 22 a that extend longitudinally away from thetubular member 11.

[0027]FIG. 1a illustrates in detail one of the T-shaped or I-shapedattachment flanges 20 which is also laser cut from the skeletal tubularmember 11 at the proximal end of one of the proximal legs 18. TheT-shaped or I-shaped attachment flange 20 is slightly arched andoriented on the proximal leg 18 such that the arch coincides with thewall 12 of the tubular member 11.

[0028]FIG. 2 illustrates the repetitive cell pattern of the skeletaltubular member 11. The cell pattern may be formed by interconnectedundulating members 24 and struts 26. Each strut 26 has a proximal end 28and a distal end 30. Each undulating member 24 has a proximal end 32, aplurality of peaks 34, and a distal end 36. The proximal end 32 is theleft tip of an undulating member 24. The peaks 34 are the highest andlowest points of an undulating member 24. The distal end 36 is the righttip of an undulating member 24.

[0029] The undulating members 24 and struts 26 are interconnected in away to maximize “nesting” of the undulating members 24 to therebyminimize the compressed diameter of the skeletal tubular member 11during deployment. The proximal end 28 of each strut 26 is attached to apeak 34 of an undulating member 24 and the distal end 30 of the samestrut 26 is attached to a peak 34 of an adjacent undulating member 24.This interconnection of undulating members 24 and struts 26 permits thecells 14 of the skeletal tubular member 11 to collapse and allows thetubular member 11 to attain a compressed diameter.

[0030] The repetitive cell pattern of the skeletal tubular member 11 mayalso be formed by interconnected sinusoidal members 38 and struts 26.Each sinusoidal member 38 has a proximal end 40, a plurality of positivepeaks 42, a plurality of negative peaks 44, and a distal end 45. Theproximal end 40 is the left tip of a sinusoidal member 38. The positivepeaks 42 are the highest points of a sinusoidal member 38. The negativepeaks 44 are the lowest points of a sinusoidal member 38. The distal end45 is the right tip of a sinusoidal member 38.

[0031] The sinusoidal members 38 and struts 26 are interconnected in away to maximize “nesting” of the sinusoidal members 38 therebyminimizing the compressed diameter of the skeletal tubular member 11during deployment. Each strut 26 connects a positive peak 42 of asinusoidal member 38 with a negative peak 44 of an adjacent sinusoidalmember 38. This interconnection of sinusoidal members 38 and struts 26permits the cells 14 of the skeletal tubular member 11 to collapse andallows the tubular member 11 to attain a compressed diameter.

[0032] Also illustrated in FIG. 2 are the proximal legs 18, 18 a, and 18b and the distal legs 22 and 22 a. In the repetitive cell pattern formedby undulating members 24 and struts 26, the proximal legs 18, 18 a, and18 b are connected to the proximal ends 32 of undulating members 24, andthe distal legs 22 and 22 a are connected to the distal ends 36 ofundulating members 24. In the repetitive cell pattern formed bysinusoidal members 38 and struts 26, the proximal legs 18, 18 a, and 18b are connected to the proximal ends 40 of sinusoidal members 38, andthe distal legs 22 and 22 a are connected to the distal ends 45 ofsinusoidal members 38.

[0033] It should be understood that the stent device of the presentinvention may alternatively be coated with an agent, such as heparin orrapamycin, to prevent stenosis or restenosis of the vessel. Examples ofsuch coatings are disclosed in U.S. Pat. Nos. 5,288,711; 5,516,781;5,563,146 and 5,646,160. The disclosures in these patents areincorporated herein by reference.

[0034]FIG. 3 illustrates the deployment system 46 for the stent device10. The deployment system 46 includes an outer sheath 48 which isessentially an elongated tubular member, similar to ordinary guidingcatheters which are well known to those of ordinary skill in the art.The deployment system 46 also includes an inner shaft 50 locatedcoaxially within the outer sheath 48 prior to deployment. The innershaft 50 has a distal end 52 and a proximal end (not shown). The distalend 52 of the shaft 50 has three grooves 54, 54 a, and 54 b disposedthereon. When the deployment system 46 is not fully deployed, the stentdevice 10 is located within the outer sheath 48. The T-shaped orI-shaped attachment flanges 20, 20 a, and 20 b on the proximal legs 18,18 a, and 18 b of the tubular member 11 are set within the grooves 54,54 a, and 54 b of the inner shaft 50, thereby releasably attaching thestent device 10 to the inner shaft 50. This deployment system isdescribed in more detail in U.S. Pat. No. 6,267,783 assigned to the sameassignee as the present patent application. The disclosure in thispatent is incorporated herein by reference and made a part of thepresent patent application.

[0035] A novel system has been disclosed in which a self-expanding stentdevice comprises a laser cut, skeletal tubular member having a pluralityof cells. Although a preferred embodiment of the invention has beendescribed, it is to be understood that various modifications may be madeby those skilled in the art without departing from the scope of theclaims which follow.

What is claimed is:
 1. A self-expanding aneurysm cover comprising: asmall diameter, skeletal, tubular member having a thin wall and having aproximal end and a distal end; said wall of said tubular membercomprising a plurality of cells which are formed by a plurality ofinterconnected, generally undulating members and a plurality of rows ofsingle-strand, unbranched struts; said undulating members extendinggenerally in the same direction as the longitudinal axis of said tubularmember, said undulating members being generally parallel to each other,forming a plurality of parallel rows; each undulating member having apositive peak and a negative peak; each strut having a proximal end anda distal end; said undulating members and said struts within a row beinginterconnected and having a repeating pattern in which the ends of saidstrut are respectively attached to the positive and negative peaks ofadjacent undulating members, with adjacent struts extending in the samedirection in the same row.
 2. The aneurysm cover of claim 1 in whichsaid struts of adjacent rows extend transversely to each other.
 3. Theaneurysm cover of claim 1 in which each of said undulating members has aplurality of positive peaks and negative peaks arranged in alternatingorder.
 4. The aneurysm cover of claim 3 in which said struts of adjacentrows extend transversely to each other.
 5. A self-expanding aneurysmcover as defined in claim 1 in which said skeletal, tubular member has asmall, compressed diameter for delivery within a vessel and a normallybiased, expanded diameter for retaining said tubular member against thewalls of a vessel and arranged whereby, when said skeletal, tubularmember is compressed to its small diameter, the positive and negativepeaks of said undulating members pull upon the proximal ends of saidstruts, and the distal ends of said struts pull upon positive andnegative peaks of adjacent undulating members, causing said cells ofsaid tubular member to collapse and thereby causing said tubular memberto obtain said small diameter.
 6. A self-expanding aneurysm cover asdefined in claim 1, wherein said skeletal, tubular member includes atleast two proximal legs, said proximal legs extending generally parallelto the longitudinal axis of said tubular member, and being attached tothe proximal end of said skeletal, tubular member, at least one proximalleg including a T-shaped attachment flange.
 7. A self-expanding aneurysmcover as defined in claim 6, wherein said proximal legs are biasedoutwardly from the longitudinal axis of said skeletal, tubular member.8. A self-expanding aneurysm cover as defined in claim 6, wherein saidproximal legs include a radiopaque marker.
 9. A self-expanding aneurysmcover as defined in claim 1, wherein said tubular member includes atleast one distal leg, said distal leg extending generally parallel tothe longitudinal axis of said tubular member and being attached to thedistal end of said skeletal, tubular member.
 10. A self-expandinganeurysm cover as defined in claim 9, wherein said distal leg includes aradiopaque marker.
 11. A self-expanding aneurysm cover as defined inclaim 1, wherein said skeletal, tubular member is constructed from anickel-titanium alloy.
 12. A self-expanding aneurysm cover as defined inclaim 2, wherein said skeletal, tubular member includes at least twoproximal legs, said proximal legs extending generally parallel to thelongitudinal axis of said tubular member, and are attached to theproximal end of said skeletal tubular member, at least one proximal endincluding a T-shaped attachment flange.
 13. A self-expanding aneurysmcover as defined in claim 12, wherein said proximal legs are biasedoutwardly from the longitudinal axis of said skeletal, tubular member.14. A self-expanding aneurysm cover as defined in claim 12, wherein saidproximal legs include a radiopaque marker.
 15. A self-expanding aneurysmcover as defined in claim 11, wherein one of said legs includes aradiopaque marker.
 16. A self-expanding stent device comprising: a smalldiameter, skeletal tubular member having a thin wall and having aproximal end and a distal end; said wall of said tubular membercomprised of a plurality of cells which are formed by a plurality ofgenerally undulating members and a plurality of single strand,unbranched struts; said struts interconnecting the undulating members,in which said undulating members are generally parallel with thelongitudinal axis of said tubular member and are generally parallel toeach other; each undulating member has a positive peak and a negativepeak; each strut has a proximal end and a distal end; a first undulatingmember and said struts within a first row have a repeating pattern inwhich the proximal ends of each of said struts are attached to negativepeaks of said undulating member and the distal ends of each of saidstruts of said first row are attached to positive peaks of a second,adjacent undulating member, and the proximal ends of an adjacent row ofstruts are attached to positive peaks of said first undulating member;and the distal ends of each of said struts of said adjacent row areattached to negative peaks of a third, adjacent undulating member; thestruts in each row extending in the same direction, and the struts inadjacent rows extending transversely to each other.
 17. The aneurismcover of claim 16 in which each of said undulating members has aplurality of positive peaks and negative peaks arranged in alternatingorder.
 18. A self-expanding aneurysm cover as defined in claim 16 inwhich said skeletal, tubular member has a small, compressed diameter fordelivery within a vessel and a normally biased, expanded diameter forretaining said tubular member against the walls of a vessel and arrangedwhereby, when said skeletal, tubular member is compressed to its smalldiameter, the positive and negative peaks of said undulating memberspull upon the proximal ends of said struts, and the distal ends of saidstruts pull upon positive and negative peaks of adjacent undulatingmembers, causing said cells of said tubular member to collapse andthereby causing said tubular member to obtain said small diameter.
 19. Aself-expanding aneurysm cover as defined in claim 16, wherein saidskeletal, tubular member includes at least two proximal legs, saidproximal legs extending generally parallel to the longitudinal axis ofsaid tubular member, and being attached to the proximal end of saidskeletal, tubular member, at least one proximal leg including a T-shapedattachment flange.
 20. A self-expanding aneurysm cover as defined inclaim 19, wherein said proximal legs are biased outwardly from thelongitudinal axis of said skeletal, tubular member.
 21. A self-expandinganeurysm cover as defined in claim 19, wherein said proximal legsinclude a radiopaque marker.
 22. A self-expanding aneurysm cover asdefined in claim 16, wherein said tubular member includes at least onedistal leg, said distal leg extending generally parallel to thelongitudinal axis of said tubular member and being attached to thedistal end of said skeletal, tubular member.
 23. A self-expandinganeurysm cover as defined in claim 22, wherein said distal leg includesa radiopaque marker.
 24. A self-expanding aneurysm cover as defined inclaim 16, wherein said skeletal, tubular member is constructed from anickel-titanium alloy.